CHEMISTRY 1412 GENERAL CHEMISTRY II

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Lab access

Please keep in mind that in order to access the lab you must:

- Have done the corresponding prelab work (-5 points of penalty).
- Comply with the dressing code.
- Have the lab coat (safety goggles will be provided).
- have watched the ACS safety video
- Have learned the lab equipment and procedure

Laboratory reports guidelines

The laboratory report is divided in two sessions:** Pre-Lab** to be prepared before the lab, and **Post-Lab** to be prepared after the experiment. Both have to be uploaded in turnitin.com, as a **MS-Word file**. *Y*ou can upload the fine **only once, and you cannot resubmit. **

You have to use the following template files

Here some examples of lab reports.

lab1.pdf , lab2.pdf

Class turnitin.com Class ID: 16298199

Pre-lab requirements

It must contain:

1. One paragraph describing __procedure__ of the experiment.

2. The answers of the "pre-lab" questions of the given experiment, see lab-manual.

Post-lab requirements

The purpose of this experiment is to determine the molar heat of vaporization of water ( Δ H where P is the vapor pressure of water and T is the temperature of the water in Kelvin, R is a the gas constant (8.314 J/mol K) and A is a constant. The Clausius-Clapeyron equation exhibits a relationship between the natural log of the vapor pressure (ln P) of a liquid and the reciprocal of the temperature (1/T) such that by plotting ln P (y-axis) vs 1/T (x-axis) a straight line occurs with a slope =-Δ H A liquid boils when its vapor pressure matches the prevailing atmospheric pressure so as atmospheric pressure decreases so does the temperature at which the liquid boils. This experiment will reduce the apparent atmospheric pressure in a closed flask of water and measure the boiling temperatures of the water under these different conditions of apparent atmospheric pressured A set of corresponding vapor pressure and temperature values will be collected for the water under these conditions. The collected set of vapor pressure/temperature data are then plotted _{vap} can be calculated: Δ H The literature value listed for the molar heat of vaporization of water is Δ . ^{f}
Part II:
This section should contain the tear-out
This section should contain all calculations necessary to obtain the experimental results from the experimental data and should be on the tear-out data sheets. Extra pages may be included for calculations if there is not enough room on the tear-out sheets.
The Clausius-Clapeyron equation gives the relationship between the vapor pressure and temperature of a liquid
Given that a liquid boils when its vapor pressure is equal to the atmospheric pressure, we were able to acquire ^{2} = 0.9989 (1.000 is a perfect fit). The correlation coefficient indicates that the data points fit the straight best-fit line quite well. The slope of the line (slope = - 4635.1 K) is related to the molar heat of vaporization of water: ^{c}Δ H The calculated value of Δ H _{vap} = 40.67 kJ/mol and the error is 5.24%. It should be noted that the result for the calculated molar heat of vaporization is only as good as the slope of the best straight-line fit of the data. In addition, the calibration of the thermister and the pressure sensors is extremely important in the collection of accurate data. If the calibration of either (or both) of the units is incorrect, a small variation in slope can greatly affect the calculated value^{e} (a slope of – 3635 K instead of – 4635 K would produce a Δ H^{f}_{vap} = 30.2 kJ/mol, over 10 kJ/mol lower that the literature value!). |
_{wap}) and the mathematical relationship (Clausius-Clapeyron equation) is explained.
very brief and conceptual description of how the data is to be obtained may be necessary, but any specific experimental procedure should not be given in the introduction.
Note: the spacing is 1.5 lines to allow for easier reading, comments and corrections.
Make sure all data is given in the correct number of significant digits and has the
Calculations should be organized and written neatly, showing all units.
There should be a brief discussion of what could cause error in the experiment—and this is ^{f}not ”I misread the balance”! This should be error that can occur from conditions in the collection of data and the processing of the data. |